Lateral Manipulation of Atomic Vacancies in Ultrathin Insulating Films

Li, Zhe; Chen, Hsin‐Yi Tiffany; Schouteden, Koen; Lauwaet, Koen; Janssens, Ewald; Haesendonck, Chris Van; Pacchioni, Gianfranco; Lievens, Peter

doi:10.1021/acsnano.5b00840

Cited by 15 publications

(10 citation statements)

References 54 publications

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“…It is clear that further advances in high-resolution imaging with CO tips call for a detailed characterization of the electronic charge distribution of CO–metal apexes and its contribution to the AFM contrast. Cl vacancies in the top layer of NaCl(100), which have already been extensively studied using both STM and AFM, − provide an ideal model system for this task. First, these localized ionic defects provide unambiguous lattice site identification.…”

Section: Resultsmentioning

confidence: 99%

“…Consecutively, a CO tip was prepared by picking up a single CO molecule from NaCl . The Cl vacancy can be unambiguously identified by its characteristic features in STS, by KPFM, or by atomically resolved STM , and AFM images …”

Section: Resultsmentioning

confidence: 99%

“…Consecutively, a CO tip was prepared by picking up a single CO molecule from NaCl. 1 The Cl vacancy can be unambiguously identified by its characteristic features in STS, 23 by KPFM, 24 or by atomically resolved STM 23,25 and AFM images. 26 Figure 1 presents experimental AFM raw data of a Cl vacancy acquired with a CO tip as a function of tip−sample distance.…”

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confidence: 99%

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The Electric Field of CO Tips and Its Relevance for Atomic Force Microscopy

et al. 2016

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Metal tips decorated with CO molecules have paved the way for an impressively high resolution in atomic force microscopy (AFM). Although Pauli repulsion and the associated CO tilting play a dominant role at short distances, experiments on polar and metallic systems show that electrostatic interactions are necessary to understand the complex contrast observed and its distance evolution. Attempts to describe those interactions in terms of a single electrostatic dipole replacing the tip have led to contradictory statements about its nature and strength. Here, we solve this puzzle with a comprehensive experimental and theoretical characterization of the AFM contrast on Cl vacancies. Our model, based on density functional theory (DFT) calculations, reproduces the complex evolution of the contrast between both the Na cation and Cl anion sites, and the positively charged vacancy as a function of tip height, and highlights the key contribution of electrostatic interactions for tip-sample distances larger than 500 pm. For smaller separations, Pauli repulsion and the associated CO tilting start to dominate the contrast. The electrostatic field of the CO-metal tip can be represented by the superposition of the fields from the metal tip and the CO molecule. The long-range behavior is defined by the metal tip that contributes the field of a dipole with its positive pole at the apex. At short-range, the CO exhibits an opposite field that prevails. The interplay of these fields, with opposite sign and rather different spatial extension, is crucial to describe the contrast evolution as a function of the tip height.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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The Electric Field of CO Tips and Its Relevance for Atomic Force Microscopy

et al. 2016

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“…While ideal for experiments comprising up to several hundreds of constituents, the absence of a large-scale defect-free detectable grid on this surface prohibits the construction of architectures involving correlated lattice-placement of atoms separated by more than a few nanometres. Moreover, thermal motion of the adatoms restricts the technique to temperatures below 10 K. As we demonstrate below, we find that manipulation of missing atoms in a surface (vacancies) 16 , as opposed to additional atoms atop, permits a dramatic leap forward in our capability to build functional devices on the atomic scale.To this purpose, we take advantage of the self-assembly of chlorine atoms on the Cu(100) surface [17][18][19][20] , forming a flat two-dimensional lattice with several convenient properties. First, it provides large areas of a perfect template grid, with a controllable coverage of vacancies.…”

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confidence: 85%

A kilobyte rewritable atomic memory

et al. 2016

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The advent of devices based on single dopants, such as the single atom transistor 1 , the single spin magnetometer 2,3 and the single atom memory 4 , motivates the quest for strategies that permit to control matter with atomic precision. Manipulation of individual atoms by means of low-temperature scanning tunnelling microscopy 5 provides ways to store data in atoms, encoded either into their charge state 6,7 , magnetization state 8-10 or lattice position 11 . A defining challenge at this stage is the controlled integration of these individual functional atoms into extended, scalable atomic circuits. Here we present a robust digital atomic scale memory of up to 1 kilobyte (8,000 bits) using an array of individual surface vacancies in a chlorine terminated Cu(100) surface. The memory can be read and rewritten automatically by means of atomic scale markers, and offers an areal density of 502 Terabits per square inch, outperforming state-of-the-art hard disk drives by three orders of magnitude. Furthermore, the chlorine vacancies are found to be stable at temperatures up to 77 K, offering prospects for expanding large-scale atomic assembly towards ambient conditions.Since the first demonstration of atom manipulation, 25 years ago 5 , the preferred approach for assembling atomic arrangements has been the lateral positioning of atoms or molecules evaporated onto a flat metal surface, most notably the (111) crystal surface of copper [12][13][14][15] . While ideal for experiments comprising up to several hundreds of constituents, the absence of a large-scale defect-free detectable grid on this surface prohibits the construction of architectures involving correlated lattice-placement of atoms separated by more than a few nanometres. Moreover, thermal motion of the adatoms restricts the technique to temperatures below 10 K. As we demonstrate below, we find that manipulation of missing atoms in a surface (vacancies) 16 , as opposed to additional atoms atop, permits a dramatic leap forward in our capability to build functional devices on the atomic scale.To this purpose, we take advantage of the self-assembly of chlorine atoms on the Cu(100) surface [17][18][19][20] , forming a flat two-dimensional lattice with several convenient properties. First, it provides large areas of a perfect template grid, with a controllable coverage of vacancies. Second, the chlorine lattice remains stable up to a large density of vacancies and up to relatively high temperature (77 K). And third, critical for our purpose, the precise location of the vacancies can be manipulated by STM with a very high level of control (and without the need to pick-up atoms with the tip, i.e. vertical atom manipulation). As we show below, these properties allow us to position thousands of vacancies at predefined atomic sites in a reasonable timeframe.The chlorinated copper surface is prepared in ultra-high vacuum through the evaporation of anhydrous CuCl 2 powder heated to 300 °C onto a clean Cu(100) crystal surface. The crystal is pre-heated to 100-150 °C prior...

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“…Overall, many schemes have been proposed, among which the direct manipulating and positioning of the right atoms and molecules in the right place is the most attractive one. This can be divided into two categories: one is to manipulate the atom and molecule one by one (representing point-by-point manipulation), such as STM technology [12,13,14,15,16,17,18,19,20,21,22,23]; the other is to manipulate hundreds of millions of atoms and molecules (clusters) simultaneously (representing macroscopic manipulation), such as magnetron sputtering [24,25], molecular beam epitaxy [26,27], evaporation plating [28], sublimation [29], etc. Obviously, the former can manipulate atoms and molecules precisely to the designed places to manufacture objects [12,13,14,15,16,17,18,19,20,21,22,23]; however, this is practically difficult for large-sized objects [30].…”

Section: Introductionmentioning

confidence: 99%

A Universal Solution of Controlling the Distribution of Multimaterials during Macroscopic Manipulation via a Microtopography-Guided Substrate

Zhang

et al. 2018

Nanomaterials

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Any object can be considered as a spatial distribution of atoms and molecules; in this sense, we can manufacture any object as long as the precise distribution of atoms and molecules is achieved. However, the current point-by-point methods to precisely manipulate single atoms and single molecules, such as the scanning tunneling microscope (STM), have difficulty in manipulating a large quantity of materials within an acceptable time. The macroscopic manipulation techniques, such as magnetron sputtering, molecular beam epitaxy, and evaporation, could not precisely control the distribution of materials. Herein, we take a step back and present a universal method of controlling the distribution of multimaterails during macroscopic manipulation via microtopography-guided substrates. For any given target distribution of multimaterials in a plane, the complicated lateral distribution of multimaterials was firstly transformed into a simple spatial lamellar body. Then, a deposition mathematical model was first established based on a mathematical transformation. Meanwhile, the microtopographic substrate can be fabricated according to target distribution based on the deposition mathematical model. Following this, the deposition was implemented on the substrate according to the designed sequence and thickness of each material, resulting in the formation of the deposition body on the substrate. Finally, the actual distribution was obtained on a certain section in the deposition body by removing the upside materials. The actual distribution can mimic the target one with a controllable accuracy. Furthermore, two experiments were performed to validate our method. As a result, we provide a feasible and scalable solution for controlling the distribution of multimaterials, and point out the direction of improving the position accuracy of each material. We may achieve real molecular manufacturing and nano-manufacturing if the position accuracy of distribution approaches the atomic level.

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Lateral Manipulation of Atomic Vacancies in Ultrathin Insulating Films

Cited by 15 publications

References 54 publications

The Electric Field of CO Tips and Its Relevance for Atomic Force Microscopy

The Electric Field of CO Tips and Its Relevance for Atomic Force Microscopy

A kilobyte rewritable atomic memory

A Universal Solution of Controlling the Distribution of Multimaterials during Macroscopic Manipulation via a Microtopography-Guided Substrate

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